Why You Can't Blame El Niño for Extreme Weather (Yet)

Over the past several months, there has been a lot of hype about an upcoming El Niño event in the tropical Pacific Ocean, which would upend global weather patterns in ways that might squelch the California drought and lead to a record warm year worldwide.

El Niño conditions are characterized by above average sea surface temperatures in the central and eastern tropical Pacific Ocean, as well as changes in the trade winds that typically blow from east to west across the tropical Pacific. In addition, there are changes to where towering thunderstorms form across the tropics, with a shift in heavy rains away from the western Pacific.

Despite the fact that sea surface temperatures are above average in some of the right spots in the Pacific, El Niño conditions are not quite mature enough to declare it "here" yet. This is partly the ocean's fault and partly the atmosphere's.

Come on, get it together, guys.

Sea surface temperatures show above average water in the eastern equatorial Pacific Ocean, which is a sign of an El Nino.

Image: NOAA/ESRL

The formation of El Niño is a lot like a first date. There's nervous conversation between the air and the ocean, both of them showing a hypersensitivity to each other's words. If the mood isn't right, there won't be a second date or a third. But every once in a while (in this case, every three to seven years), things click — and they last for a year or two before breaking up again.

In this case, the ocean knows what it wants, but the atmosphere is playing hard to get.

Climate scientists at the National Oceanic and Atmospheric Administration (NOAA) and the International Research Institute for Climate and Society (IRI) said on Thursday that they still anticipate an El Niño event will take place within the next six months or so, with the odds of one peaking at 82% for the November through January time frame.

The evolution of a strong Kelvin Wave, transporting warm water from west to east across the Pacific (right to left). Note the cooler ocean temperatures in the western Pacific in the bottom image, which shows the lack of another Kelvin Wave.

Image: Australian Bureau of Meteorology

Stephen Baxter, a forecaster at NOAA's Climate Prediction Center in College Park, Maryland, says the latest observations show there has been “a little bit of a slowdown in what we were thinking would occur in terms of an El Niño developing.”

The problem, Baxter says, is that while the sea surface temperatures are above average across much of the tropical Pacific, the atmospheric signs of an El Niño have not yet shown up. Such signs includes increased thunderstorm activity in the central tropical Pacific and reduced or reversed trade winds.

Typical winter weather pattern across North America during an El Nino event.

Image: NOAA

The Australian Bureau of Meteorology, which also closely monitors El Niño development, says the ocean has slowed down its warming trend. Areas of warmer than average water temperatures in the western Pacific, near Indonesia, are also atypical for an El Niño, the Bureau said in an update on Tuesday.

"There is some indication that the atmosphere has become a little more responsive," Baxter said. One indication of a developing El Niño is a burst of westerly winds, which can in turn cause a ripple of warmer than average water to slosh from the western Pacific to the east side, jump-starting an event. This is known as a Kelvin Wave, and it happened this past spring, but it has not happened since.

“There is some potential over the next few weeks that we could have at least a weak westerly wind burst,” Baxter added. Furthermore, even without another westerly wind burst, which could induce another Kelvin Wave, the atmosphere and ocean system "is still on track toward the development of El Niño,” he said.

Yet Baxter, as well as the IRI and Bureau of Meteorology all cautioned against thinking that the El Niño will be an intense one. Baxter, in a call with reporters on Thursday, said the Climate Prediction Center "hasn't been kind" to the view that there will be a strong El Niño.

Equatorial upper ocean heat anomalies (deg C) during the past several months, showing a Kelvin Wave (outlined by the parallel lines) and lack of warm water moving from the western Pacific to the east recently (circled).

Image: NOAA/CPC

El Niño watchers are keeping a close eye on the updates from the forecast centers. In order for the CPC to change their current El Niño "watch" to an "advisory," the ocean temperatures in part of the equatorial Pacific need to be at least 0.5 degrees Celsius above average (or 0.9 degrees Fahrenheit above average), "along with consistent atmospheric factors."

In addition, these anomalies have to be predicted to persist for at least three straight months.

So far, those conditions have not been met. But you never know when the atmosphere and ocean will finally click, sparking an event.

Mashable
is a global, multi-platform media and entertainment company. Powered by its own proprietary technology, Mashable is the go-to source for tech, digital culture and entertainment content for its dedicated and influential audience around the globe.